This invention relates to containers and to a method for manufacturing containers. More particularly, but not exclusively, this invention relates to a sachet for storing and dispensing liquids, pastes, powders or similar substances.
A number of different types of breakable sachets are known in the art. These include sachets having a relatively flexible pouch adhered to a flexible relatively stiffer material, the stiffer material having a linear line of weakness therein, allowing opening of the sachet by folding the container about the line of weakness, thus breaking the stiffer material along such line.
These types of sachets tend to suffer from the disadvantage that in order to manufacture such sachets to be robust enough to withstand the rigors of transit or storage, they must have a degree of resistance to breakage, rendering them difficult to break open in a controlled manner as intended.
A number of solutions for facilitating breakage of such sachets have been proposed, including those disclosed in PCT application PCT/NZ96/00078 and U.S. Pat. No. 4,493,574. The proposed solutions suffer from the disadvantages of requiring relatively complex manufacturing techniques and therefore being relatively more expensive to produce, and/or rendering controlled dispensing of the contents of the sachet difficult.
Another disadvantage of the known containers is that pressure is built up inside the container when the container is folded about the line of weakness and they tend to open in a sudden uncontrolled fashion, so that the contents squirt out of the container. The reason for this uncontrolled opening is mainly due to the fact that the line of weakness is linear. The linear line of weakness presents the further disadvantage that the first wall breaks right through from edge to edge, even though the line of weakness is not demarcated up to the edges, so that the integrity of the container after opening is compromised.
Other containers of this type are disclosed in the following patents AU19159/83; AU47827/85; AU21286/83; U.S. Pat. No. 3,905,479; GB1572603; AU49661/79; EP81791; EP95335; AU16340/88; U.S. Pat. No. 4,130,245; U.S. Pat. No. 3,453,661; GB1152552; U.S. Pat. No. 4,557,377; U.S. Pat. No. 5,373,966; and U.S. Pat. No. 2,530,400. These containers all suffer from one disadvantage or the other such as that they are relatively expensive, bulky or have limited applications.